package org.apache.lucene.search.payloads;

import org.apache.lucene.search.Explanation;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Returns the maximum payload score seen, else 1 if there are no payloads on the doc.
 * <p/>
 * Is thread safe and completely reusable.
 *
 **/
public class MaxPayloadFunction extends PayloadFunction {
    @Override
    public float currentScore(int docId, String field, int start, int end, int numPayloadsSeen, float currentScore, float currentPayloadScore) {
        if (numPayloadsSeen == 0) {
            return currentPayloadScore;
        } else {
            return Math.max(currentPayloadScore, currentScore);
        }
    }

    @Override
    public float docScore(int docId, String field, int numPayloadsSeen, float payloadScore) {
        return numPayloadsSeen > 0 ? payloadScore : 1;
    }

    @Override
    public Explanation explain(int doc, int numPayloadsSeen, float payloadScore) {
        Explanation expl = new Explanation();
        float maxPayloadScore = (numPayloadsSeen > 0 ? payloadScore : 1);
        expl.setValue(maxPayloadScore);
        expl.setDescription("MaxPayloadFunction(...)");
        return expl;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + this.getClass().hashCode();
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        return true;
    }
}
